Ancient viruses may have aided humans in evolution
A groundbreaking discovery led by evolutionary biologist Alex de Mendoza Soler, at Queen Mary University of London, reveals that ancient viruses may have significantly contributed to our evolution. The team found remnants of ancient viral genomes within the DNA of a single-celled organism, Amoebidium, which shares a common ancestor with complex organisms like humans. "It's like finding Trojan horses hiding inside the Amoebidium's DNA," said de Mendoza Soler, suggesting these viral insertions could have enhanced survival by contributing beneficial genes.
Amoebidium's unique coping mechanism unveiled
The research indicates that Amoebidium recurrently mixes its genome with that of its giant virus predators, a potentially lethal process. However, de Mendoza Soler explained that the organism has developed a coping mechanism to silence these foreign genes, by chemically modifying one of the four letters in the DNA alphabet, using a process called 5-methylcytosine (5mC). "These viral insertions are potentially harmful, but Amoebidium seems to be keeping them in check by chemically silencing them," he said.
Unearthing the pre-animal roots of a key enzyme
The researchers discovered that Amoebidium produces an enzyme called DNMT1, which modifies the base cytosine or 'C' in the DNA sequence. This enzyme is found in all multi-celled organisms, and its presence in Amoebidium suggests pre-animal roots for this enzyme. "These findings challenge our understanding of the relationship between viruses and their hosts," de Mendoza Soler stated, implying a more complex relationship than traditionally perceived.
Viral insertions: A dynamic process in evolution
The team proposed that Amoebidium's coping mechanism not only allows survival against the influx of giant virus DNA but also enables its incorporation into their lineage. Comparing the genomes of various isolated Amoebidia, they found a high level of diversity across the viral material, indicating an ongoing and dynamic process. "Viral insertions may have played a role in the evolution of complex organisms by providing them with new genes," de Mendoza Soler explained.
